Nature Materials

Tissue-engineered skeletal muscle offers robotics unique advantages in energy density, adaptability, and self-repair, but current biohybrid machines couple muscle directly to artificial skeletons, limiting net force output and requiring continuous stimulation maintain mechanism positions. Here, we introduce a biohybrid bistable switching mechanism that converts antagonistic muscle contractions to snap-through actuation of an elastomeric four-bar flexure, maintaining stable positions without energy consumption. We decouple passive muscle pre-tensioning from flexure operation with thin-film elastomer resistance bands, enabling fine tuning of spring stiffness and force to match muscle mechanical output envelopes. Leveraging mesoscale additive manufacturing, spin coating, and replica molding techniques, components are integrated into a millimeter-scale linear stage to axially align muscles with artificial components. Our prototype achieves reversible toggling between bistable states with a 130 ms switching time, establishing skeletal muscle actuators as viable electromechanical switches, and broadening biohybrid robotics towards novel applications such as grippers, valves, and mechanical computers.

The actin cytoskeleton is a self-assembled material that acts as the mechanical scaffold of the cell. Within the cell, protein cross-linkers organize actin filaments into assemblies with various microstructures that support distinct physiological functions. These protein cross-linkers differ in structural features. To decouple the role of individual cross-linker properties in actin assembly microstructure and mechanics, we synthesize programmable cross-linkers using a DNA linker coupled to binding domains. We find that high affinity cross-linkers induce actin bundling, while low affinity cross-linkers form actin networks. Myosin II motors remodel and contract all cross-linked networks tested in distinct ways from uncross-linked networks. We find that networks with high affinity cross-linkers have different myosin induced dynamics than networks with low affinity cross-linkers. This research expands our understanding of how cells regulate their mechanics and microstructures, while also providing insight towards the structure-property relationship in complex soft materials.

Engineered human neuromuscular models are limited by a trade-off between biological fidelity and architectural control: self-assembled organoids organize stochastically, while engineered 3D tissues impose anisotropy through passive tension at the edges without internal guidance. Here we encode architectural guidance into human neuromuscular tissues by coupling a three-dimensional, cell-laden biomatrix to a xolographically printed hydrogel substrate featuring sub-millimeter surface topography. We demonstrate that grooved substrates increase human primary myotube alignment and maturation in the overlying 3D tissue, while guiding directional axon extension from human iPSC-derived motor neuron spheroids. We show that combining both cell types along a shared alignment axis establishes functional neuromuscular connectivity, evidenced by acetylcholine receptor clustering, glutamate-evoked contraction and its blockade by d-tubocurarine (curare), and yields innervation coverage of centimeter scale tissues. Overall, this platform combines compliant substrates, mesoscale tissue architectural guidance, and human-relevant cell biology in a single untethered construct for studies of neuromuscular tissue development and function.

The development of novel mechanomedicine technologies critically depends on the ability to administer a well-defined mechanical dosage to cells. Unlike chemical cues, mechanical signals are vectorial rather than scalar, making their precise delivery inherently complex. When external mechanical stimuli are applied to cells seeded on a flat substrate, the mechanical dose experienced by each cell varies depending on its orientation and conformation, rendering consistent and effective mechano-modulation impractical. Here, we introduce a substrate-guided mechanical stimulation strategy that standardizes mechanical dose delivery at the population level by controlling cell orientation. Using nanogrooved PDMS substrates integrated into a uniaxial stretching platform, we induced coherent alignment of NIH3T3 fibroblasts and their mechanosensitive subcellular structures along the direction of applied strains. Cells cultured on flat or nanogrooved substrates were subjected to sustained uniaxial strains of 8% and 29%, and their responses were quantified in real time by live-cell fluorescence imaging. Nanogroove-induced alignment enabled uniform transmission of substrate strain to focal adhesions and the cytoskeleton, resulting in coherent and quantifiable nuclear deformation across the cell population. In contrast, cells on flat substrates exhibited orientation-dependent deformation modes that canceled out at the population level, leading to heterogeneous and attenuated responses. While cellular adaptation to sustained strain was primarily governed by strain magnitude, substrate-guided alignment markedly reduced cell-to-cell variability in mechanical signal perception. Overall, this work establishes cell alignment as a key parameter for standardizing mechanical dose delivery and improving the reproducibility of mechanobiology experiments and the design of mechanically active biomaterials.

Cell motility drives spatial pattern formation across diverse biological systems. Here, we engineer Escherichia coli motility in semi-solid agar to control Voronoi patterns in two and three dimensions, partitioning space into regions closest to their respective inoculation seeds. Consistent with our reaction-diffusion model, we observed that collisions between expansion fronts generate either biomass depletion (''gaps'') or accumulation (''anti-gaps''), governed by the relative diffusion rates of bacteria and nutrients. By engineering strains with distinct expansion rates and tuneable motility, and by integrating these experimental data into a dynamic Voronoi model, we achieved precise control over pattern geometry. This enabled the generation of gaps with varying widths, curved boundaries, asymmetric structures, seedless regions, and complex composite patterns. Together, these findings establish bacterial Voronoi patterns as a programmable platform for engineering multicellular spatial organization, with potential applications in synthetic biology and materials science.

Scaling laws are powerful tools in material science to relate geometric and mechanical properties of materials. The actin cortex, a dynamic network beneath the plasma membrane, is essential for cellular morphogenesis, force generation, and tissue organization. Despite its critical role, the mechanical properties of the cortex itself remain poorly understood. Using the magnetic pincher, a new technique we recently developed, we directly measure the thickness (h) and elastic modulus (E) of the actin cortex in live cells, uncovering a universal scaling (E ~ h-2) across multiple cell types. Drawing an analogy to cellular solids, common in nature and material science, we identified an origin for this scaling: the volume fraction of actin filaments varies concomitantly with the cortex thickness, due to a conservation of filamentous actin quantity. Thus thinner cortices exhibit higher actin density and stiffness, while thicker cortices are sparser and softer. The relationship holds under diverse perturbations targeting myosin contractility, actin nucleation, and turnover, but is lost upon actin disassembly, highlighting its dependence on the intact actin network. Our results establish that cells, across cell types, function within a rather limited range of quantity of cortical actin filaments and primarily modulate cortex thickness to tune mechanical properties, with profound implications for cell shape regulation, tissue mechanics, and the interpretation of indentation-based mechanical measurements.

Mechanical remodeling by cancer-associated fibroblasts (CAFs) stiffens tumors and can restrict molecular transport, yet the time-resolved coupling between cellular force and matrix mechanical state is poorly defined. Here we use a microfabricated force sensor integrated with 3D CAF-collagen tissue to measure CAF-generated force and collagen stiffness continuously during pharmacological perturbation. ROCK or non-muscle myosin II inhibition reduced force and remarkably drove collagen stiffness below its initial value rather than merely arresting stiffening. This softening was prevented by broad-spectrum MMP inhibition, but only modestly altered by lysyl oxidase inhibition, supporting a competition between force-driven collagen compaction and proteolytic remodeling. Second-harmonic generation imaging showed shorter, thinner and less aligned fibers after ROCK inhibition, while fluorescence recovery after photobleaching indicated faster dextran transport. Moreover, CAF contractile adaptation depended strongly on the duration of inhibition, with reversible recovery after brief treatment, a hyper-contractile rebound following prolonged treatment and washout, and partial force recovery during continuous exposure. These findings identify CAF-matrix mechanics as a dynamic, treatment-history-dependent balance and provide a framework for designing stromal interventions that alter stiffness and transport.

During tumor growth and progression, cancer cells are exposed to sustained physical confinement and volumetric compression that can alter cell volume, cytoskeletal organization, mechanotransduction, and invasive behavior. However, whether breast cancer cells retain a compression-induced mechanical memory after release from sustained volumetric compression, and how this memory influences subsequent migration and invasion, remains poorly understood. Here, by controlling cell volume using PEG - mediated volumetric compression, we investigated the compression and post-compression recovery responses of MCF-7 breast cancer cells. Cells were compressed for four days, followed by four days of recovery after PEG removal, and analyzed using daily morphological tracking, single-cell time-lapse imaging, F-actin and YAP staining, wound healing assays, and 3D spheroid invasion assays. We show that sustained volumetric compression shifts MCF-7 cells into a compact, jammed-like, low-motility state characterized by reduced morphodynamic remodeling, suppressed collective migration, and limited spheroid invasion. In contrast, post-compression recovery induces a distinct mechanobiological state marked by increased cell area and perimeter, altered single-cell trajectories, heterogeneous F-actin remodeling, enhanced YAP nuclear localization in enlarged recovered cells, accelerated wound closure, and increased spheroid invasion and cell dissemination. These findings suggest that prior volumetric compression can prime breast cancer cells for enhanced migration and invasion after stress release, supporting post-compression recovery as a form of mechanical memory that may contribute to tumor dissemination.

Cells continuously integrate mechanical cues from the surrounding extracellular matrix to control fundamental biological processes such as proliferation and migration. Yet, studying the mechanical activity of cells in 3D over time is challenging, low-throughput, and requires specialized equipment. Here, we introduce DNA-based force-history probes, which convert transient pico-Newton forces into cumulative fluorescent signals within a mechanically adjustable DNA-crosslinked cell culture matrix. The probes provide control over signal lifetimes, allowing stress patterns to be recorded over minutes to days with tunable temporal memory. We use this system to visualize the mechanical activity of breast cancer spheroids and map the trajectories of migrating cancer cells. By combining different fluorophores and DNA-encoded signal lifetimes, we produce dual-color probes that associate temporal information to mechanical events. Overall, force-history probes provide an endpoint-readable record of mechanical cell-matrix activity, offering new opportunities for studying cell function in physiology and disease.

Cell shape changes during migration, division, or differentiation require the dynamic regulation of actin network mechanics. Actin crosslinkers are central to this regulation, controlling network connectivity and the transmission of contractile forces. A large diversity of crosslinkers exists, differing in length, domain structure, and binding kinetics, yet why cells deploy specific crosslinkers in a physiological context remains unclear. To bridge this gap, we developed a light-controlled actin crosslinker toolbox spanning three physiologically relevant lengths: ~9 nm (fascin-like), ~16 nm (fimbrin-like), and ~56 nm (alpha-actinin-like). Using magnetic pincher experiments and in silico modelling, we show that short and mid-length crosslinkers dynamically tune cortical stiffness and thickness in a density- and myosin-dependent manner, with short crosslinkers also driving pronounced stress-stiffening as the cortex is deformed. Strikingly, minute-scale activation reveals a length-dependent switch in cell behaviour: short crosslinkers cause cortical delamination, while long ones instead drive cell polarization and symmetry breaking. This switch can be overridden by perturbing actin turnover, which unlocks polarization in mid-length crosslinkers that otherwise delaminate. Crosslinker-induced polarization is not merely a local cortical event: it directs subsequent cell spreading, coupling a nanometre-scale molecular choice to a cell-scale decision about movement. Together, these findings establish a versatile optogenetic platform for manipulating actin crosslinking, and show that the cortex can encode a behavioural switch directly in its material architecture.

The exceptional mechanical properties of spider dragline silk originate from hierarchical spidroin self-assembly, yet mimicking this process to generate native-like structures remains challenging. Here, we report a metastable dimeric intermediate as an essential molecular factor for fibrillogenesis. Small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM) revealed a compact core stabilized by solvent-excluded "dry interfaces" surrounded by extended random coil regions. Within the core, a subset of the polyalanine blocks is held by side-chain packing rather than by main-chain {beta}-sheets; the majority remain exposed in the surrounding coil regions. Upon lowering the denaturant concentration, these exposed polyalanine segments pair with their counterparts at a fibril end, forming intermolecular {beta}-sheets that act as linkers and drive the stepwise end-to-end polymerization of the dimeric particles. In solution, the resulting fibrils exhibit an ordered {beta}-structure in which the polypeptide chains run parallel to the fibril axis, in contrast to amyloid-like cross-{beta}, in which the strands lie perpendicular to it; this matches key features of native silk nanofibril architecture. However, X-ray diffraction (XRD) analysis demonstrates that these native-like nanofibrils undergo an effectively irreversible transition toward amyloid-like cross-{beta} structures upon drying. Native-like fibrils are thus achievable by self-assembly, but structural control is lost during the final dehydration step. Accordingly, we propose a general principle for decoupling self-assembly from dehydration: native-like nanofibrils are formed first, then dried under conditions that restrict molecular-chain mobility (for example, mechanical constraint or immobilization on a surface), which we expect to suppress thermodynamic relaxation into cross-{beta} structures.

Surface curvature is a fundamental geometric cue in tissue morphogenesis, yet its role in guiding collective cell organization has remained elusive. Here, we show that curvature acts as a geometric control parameter that shapes supracellular alignment and chirality while modulating myogenic differentiation in myoblast tissues. Cells cultured on curved substrates self-organize into robust helical assemblies whose handedness is set, and can be reversed, by the sign of curvature: convex fibers produce right-handed helices, whereas concave channels invert the chirality. We identify a previously hidden clockwise bias in single-cell motion associated with the helical actin cytoskeleton. A minimal continuum theory coupling an effective chiral drive to curvature quantitatively captures the emergence and reversal of tissue-scale chiral alignment. On substrates with spatially varying curvature, local curvature gradients organize patterned multicellular architectures while preserving a global handedness. Curvature is also associated with myogenic state, with higher curvature linked to reduced or delayed differentiation. Together, these findings reveal how complex geometries shape the alignment, symmetry, and cellular state of living tissues.

Tissue mechanics influence diverse biological processes, yet directly linking stiffness measurements to spatially resolved molecular states in intact tissues remains challenging. Here we developed a paired-surface spatial mechanomics approach to map Young's modulus by nanoindentation on a fresh tissue surface and co-register the stiffness grid with 10x Genomics Visium HD spatial transcriptome bins from the immediately adjacent, parallel surface. Applied to the mouse ovary, which has spatially distinct compartments and undergoes extracellular matrix remodeling with cycle and age, the workflow generated >2,900 matched measurements across 21 regions of interest. Nanoindentation at 50-m grid spacing enabled millimeter-scale stiffness maps while balancing acquisition time in fresh tissues, with ~92 4-m transcriptome bins assigned to each stiffness value. Global and compartment-specific analyses associated stiffer regions with lower elastic fiber programs and higher inflammatory signaling, with age-dependent differences. This correlative strategy integrates experimentally measured mechanics with spatial omics in fresh tissues.

Matrix stiffness is a hallmark of aggressive solid tumors and strongly associated with therapeutic resistance and poor prognosis. This mechanical barrier represents a major unmet challenge in oncology, as current strategies rarely address how matrix mechanics themselves drive treatment resistance. Here, we identified ferroptosis, an iron-dependent form of cell death, as a potential long-sought vulnerability that can be exploited to eliminate mechanically resistant tumors. Using genetic and chemical approaches, we investigated how matrix stiffness sensitizes cancer cells to ferroptosis and whether this vulnerability can be therapeutically targeted. We found that cancer cells cultured on stiff matrices were more sensitive to ferroptosis than those on soft matrices, as evidenced by reduced cell viability and elevated lipid peroxidation. Furthermore, we found that matrix stiffness induced YAP activation, which upregulated its target gene SKP2, a key mediator required for the heightened ferroptosis sensitivity observed under stiff conditions. Finally, using an injectable hydrogel system, we demonstrated that stiffened tumors were resistant to chemotherapy but remained highly susceptible to ferroptosis induction, resulting in markedly reduced tumor volume and weight. Our findings established ferroptosis as a stiffness-dependent vulnerability mediated by a YAP-SKP2 signaling axis, revealing a mechanotransductive pathway that may be leveraged to target treatment-refractory tumors.

At the ocean-land interface lies a critical yet largely ignored ecosystem of tidal flats[1]. These habitats are colonized by diatoms that form thin surface biofilms, creating ecosystem-scale cellular collectives stretching meters to kilometers[2-4]. How these collectives coordinate functions across vast spatiotemporal scales remains poorly understood. This task requires both long-distance transfer and long-term storage of information[5, 6]. In cellular collectives, trigger waves have been known to provide rapid, non-attenuating signaling[7-9], while extracellular matrices allow cells to externalize structural memory[10-12]. Yet, how propagating signals and structural memory integrate to shape collective functions remains elusive. Combining field observations with laboratory reconstitution, we show that tidal-flat diatoms assemble active nematic circuits that physically wire trigger-wave routing into structural memory. Here, trigger waves recruit resting diatoms into polarized motion steered by the nematic director, and topological defects act as gates that focus or bifurcate propagating wave fronts. Memory follows a fast-read, slow-write rule: rapid signals deform the cellular nematic, while slowly evolving cell-deposited mucilage retains a hidden orientational template that guides alignment recovery. Strikingly, recurrent waves progressively remodel the nematic architecture, letting the collective reshape its future routing. Coupling rapid wave propagation to extracellular memory allows collectives to resolve the stability-plasticity dilemma, maintaining structural cohesion while adapting to recurrent stimuli. Our work reveals previously hidden adaptive nematic circuits that self-organize at ecological scales, establishing a physical framework for time-programmable active materials.

Early animal embryos undergo rapid cleavages that partition cytoplasmic volumes orders of magnitude larger than those of somatic cells1. Each division must reposition nuclei and centrosomes and distribute organelles within minutes, over distances up to hundreds of micrometers2. Cleavage furrows are positioned by microtubule asters3,4, but the mechanical mechanism for long-range transport of cytoplasmic components before cytokinesis was unknown. Here, we show that cytoplasm behaves as a locally switchable active material. Fluidization at the midplane allows bulk actomyosin to convert a local mechanical asymmetry into directed global flows of all components as a composite material. Using an actin-intact cycling Xenopus egg extract together with Xenopus and medaka embryos, we find that F-actin mechanically couples microtubule asters, organelles, nuclei and centrosomes into a gel-like composite that propagates forces over hundreds of micrometers. After mitosis, Aurora B kinase patterns a locally fluidized midplane, from which myosin-II contractility drives coherent cytoplasmic flows. A fluid dynamics model accounts for the observed flow geometry and rates. Our results reveal how local control of the material state of cytoplasm converts mitotic symmetry breaking into long-range intracellular transport and identify bulk actomyosin as the active stress generator that partitions embryonic cytoplasm as a composite gel.

Reconstituting organ development in vitro requires reproducing dynamic developmental transitions rather than only terminal tissue structures. Here, we developed MoSAIC (Modular Spatial Assembly and Integration of Cues), a modular platform that decomposes complex culture operations and subsequently integrates them to reconstruct multimodal mechano-chemical spatial cues. Using human induced pluripotent stem cells, MoSAIC enabled independent control of tissue geometry, extracellular matrix localization, physical boundaries, and morphogen gradients, while also permitting defined mechanical and chemical perturbations during development. Their integration guided a continuous ectodermal sheet through neural induction, tissue bending, and bifurcation into neural and epidermal tissues, followed by formation of a polarized neural tube structure. Spatially controlled morphogen exposure further established dorsoventral patterning, while the resulting tissue exhibited posterior neural tube identity. Using the developed model recapitulating the transition of human neurulation, MoSAIC further enables non-genetic perturbation of mechanical and chemical cues to interrogate the mechanisms governing neural tube closure.

Piconewton forces borne by individual proteins within complex assemblies underlie cell adhesion, migration, and tissue morphogenesis, yet remain difficult to image in living systems. Here, we introduce WHaloForce, a chemigenetic HaloTag-based tension sensor that converts force-dependent relief of tryptophan-mediated dye quenching into a fluorescence lifetime change. Optical tweezers revealed a switch-like unquenching transition near 5 pN, and the sensor responded reversibly to force changes in cells. WHaloForce enabled quantitative tension imaging of diverse force-bearing proteins (vinculin, E-cadherin, -catenin, and laminin) in mammalian cells, mouse tissue, and C. elegans. Bright synthetic dyes made tension measurements possible at endogenous expression levels. In C. elegans, vinculin and laminin showed opposite tension patterns between tissues, revealing distinct force-transmission routes through adhesions and the extracellular matrix. During ovulation, laminin tension accumulated over repeated stretch-relaxation cycles, scaling with cumulative loading history. WHaloForce thus offers a modular platform for imaging spatiotemporal tension patterns in living systems.

Collective cell behaviors emerge from mechanical interactions with the extracellular matrix (ECM), yet the physical principles governing long-range cell-cell communication remain elusive. Existing models assume that neighboring cells couple by strain-stiffening the ECM between them, amplifying contractility through positive feedback. Here we show that pairwise interactions are insufficient. Instead, stable mechanical communication requires opposing mechanical anchors that allow a cell to strain-stiffen the matrix on both sides. Combining ECM strain mapping, direct cell-force measurements, and live-cell imaging, we find that isolated cell pairs generate only weak, stochastic matrix strains without persistent interactions. In contrast, cells supported by opposing neighbors, or rigid beads acting as mechanical anchors, generate large bilateral matrix strains, increase effective matrix stiffness, align collagen fibers, and form stable multicellular networks. To explain these observations, we develop a predictive mechanosensitive theory introducing effective matrix stiffness and a critical contractile force governing the transition from stochastic to persistent interaction. The theory predicts, and experiments confirm, that opposing mechanical anchorage enables cells to exceed the critical force, trigger collective matrix remodeling, and compact the matrix through collagen-fiber buckling. Together, these findings provide a unifying framework for understanding collective force generation in development, wound repair, fibrosis, and tumor progression.

Epithelial tissues continuously remodel their curvature during morphogenesis, homeostasis, regeneration, and disease, yet experimental access to time-varying curvature remains limited. Here, we introduce CurvoChip, a pneumatically actuated microsystem that reversibly deforms confluent epithelial monolayers cultured on a 20-m elastic membrane into concave or convex geometries. The device operates either in a standard incubator or on a microscope stage and provides programmable control over pressure amplitude, direction, and cycling. Analytical scaling, finite-element simulations, and confocal profilometry establish predictable membrane deformation across the operating range, whereas cycling between -400 and +400 mbar for 120 cycles produces stable deflection without detectable drift or residual deformation. We further implement a three-dimensional surface-reconstruction and segmentation workflow to quantify cell and nuclear morphology on curved monolayers. Acute curvature induction produces a marked polarity-dependent response: convex deformation causes greater cell spreading and epithelial thinning than concave deformation, while nuclear projected area, thickness, and volume change in a direction- and position-dependent manner. These results show that epithelial architecture is sensitive not only to curvature magnitude but also to its orientation relative to the apico-basal axis. CurvoChip therefore provides an accessible platform for dissecting how epithelial tissues integrate dynamic geometric cues.